2
TROUBLESHOOTING 38..............................
Complete Unit Stoppage 38............................
Restart Procedure 38..................................
Alarms and Alerts 38.................................
Control Module Communication 45......................
Communication Failures 45............................
Cooling Troubleshooting 46............................
Humidi--MiZert Troubleshooting 47....................
Economizer Troubleshooting 48.........................
Heating Troubleshooting 49............................
Phase Loss Protection 52..............................
Thermistor Troubleshooting 52.........................
Transducer Troubleshooting 54.........................
Forcing Inputs and Outputs 54..........................
MAJOR SYSTEM COMPONENTS 57....................
General 57.........................................
Main Base Board (MBB) 75............................
Economizer Control Board (ECB) 77.....................
Integrated Gas Control (IGC) Board 79...................
Low Voltage Terminal Strip (TB1) 80.....................
Scrolling Marquee Display 81..........................
Accessory Navigatort Display 81.......................
Carrier Comfort Network (CCN)R Interface 81.............
Subcooler Heat Exchanger (SHX 48/50PG20--28 Only) 82....
Field--Installed Accessories 83..........................
SERVICE 86.........................................
Cleaning 86........................................
Lubrication 86......................................
Evaporator Fan Service and Replacement 89...............
Evaporator Fan Performance Adjustment 90...............
Evaporator Fan Belt Tension Adjustment 90...............
Condenser--Fan Adjustment 91..........................
NOVATION Heat Exchanger Condenser
Service and Replacement 91............................
Verify Sensor Performance 91..........................
Economizer Operation During Power Failure 91............
Evacuation 91.......................................
Refrigerant Charge 92.................................
Gas Valve Adjustment (48PG and 48PM) 96...............
High Altitude (48PG and 48PM) 96......................
Main Burners (48PG and 48PM) 96......................
Filter Drier 98.......................................
Protective Devices 98.................................
Relief Devices 98....................................
Control Circuit, 24--V 98..............................
Replacement Parts 98.................................
Diagnostic LEDs 98..................................
APPENDIX A -- LOCAL DISPLAY AND
CCN TABLES 99.....................................
APPENDI
X B -
- CONTROL MODES WITH
Humidi--MiZert SYSTEM AND ECONOMIZER 116........
APPENDIX C -- START --UP DATA 118...................
APPENDIX D -- ADDITIONAL START --UP DATA 185......
UNIT START--UP CHECKLIST 207......................
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment can be
hazardous due to system pressure and electrical components. Only
trained and qualified service personnel should install, repair, or
service air-conditioning equipment. Untrained personnel can
perform the basic maintenance functions of replacing filters.
Trained service personnel should perform all other operations.
When working on air -conditioning equipment, observe precautions
in the literature, tags and labels attached to the unit, and other
safety precautions that may apply. Follow all safety codes. Wear
safety glasses and work gloves. Use quenching cloth for unbrazing
operations. Have fire extinguishers available for all brazing
operations.
Follow all safety codes. Wear safety glasses and work gloves. Have
fire extinguisher available. Read these instructions thoroughly and
follow all warnings or cautions attached to the unit. Consult local
building codes and National Electrical Code (NEC) for special
requirements.
Recognize safety information. This is the safety--alert symbol
.
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.
Understand the signal words DANGER, WARNING, and
CAUTION. These words are used with the safety--alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies a hazard
which could result in personal injury or death. CAUTION is used
to identify unsafe practices which may result in minor personal
injury or product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability, or
operation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal
injury or death.
Before performing service or maintenance operations
on unit, turn off main power switch to unit and install
lockout tag. Ensure electrical service to rooftop unit
agrees with voltage and amperage listed on the unit
rating plate.
!
WARNING
UNIT DAMAGE HAZARD
Failure to follow this caution may cause equipment
damage.
This unit uses a microprocessor--based electronic control
system. Do not use jumpers or other tools to short out
components or to bypass or otherwise depart from
recommended procedures. Any short-- to --ground of the
control board or accompanying wiring may destroy the
electronic modules or electrical components.
CAUTION
!
48/50PG and PM
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